In transportation facilities using railroads, in order to improve the feeling of comfort of passengers or the like, an air spring is provided between a dolly and a carriage body. The air spring is provided at each of front and rear sides and left and right sides of one carriage so that the carriage body can be moved in the up-and-down direction with respect to the dolly by supplying pressurized air from a pressurized air source to the air spring or by releasing the air in the air spring to the atmosphere. When the air is supplied to or released from all of the air springs at the front, rear, left, and right sides, the carriage body can be translated up and down. When the air is supplied to only one of the left and right air springs or when, in addition to this configuration, the air is released from the other air spring, the carriage body can be inclined in the left-and-right direction (width direction).
For example, a level adjustment control for adjusting the height may be applied when the overall height of the carriage body with respect to the dolly becomes higher or lower than a predefined height. In addition, a carriage-body inclination control may be applied to incline the carriage body toward an inside of a curve in order to lessen an excessive centrifugal force which occurs due to insufficient cant of the rail when the carriage travels on a curved rail.
Patent Document 1 discloses a body height-measuring device for controlling carriage-body inclination which can execute a high-precision height measurement during carriage-body inclination control. In this technique, for the level adjustment control, one end of an on-off operation lever is integrally and rotatably coupled to a tip of a shaft which integrally rotates with an on-off operation unit of an automatic height adjustment valve, one end of an adjustment bar is connected to the tip of the on-off operation lever, the other end of the adjustment bar is connected via a bracket to the dolly, and a height-measuring encoder is provided on the shaft. When the height, which is in the up-and-down direction of the carriage body with respect to the dolly, changes; for example, when the height is reduced, the tip side of the on-off operation lever is pushed and raised via the adjustment bar, the automatic height adjustment valve is switched, the pressurized air is supplied to the air spring, and the height of the carriage body is increased. When the air spring is extended, the tip side of the on-off operation lever is pulled downward via the adjustment bar, and the supply of the pressurized air to the air spring is stopped. In this manner, a floor surface of the carriage body with respect to the dolly is controlled at a certain height.
When the carriage-body inclination control is applied, using the height-measuring encoder, the air communication system for level adjustment is blocked, an air pressure circuit system for carriage-body inclination control is activated, a small-size air supply valve is opened to start supply of air to the air spring, and then, a large-size air supply valve is opened to increase the carriage height. When the height reaches a predetermined height, the large-size air supply valve is closed and, then the small-size air supply valve is closed. When the carriage height is to be reduced, a release valve is opened to effect releasing of air from the air spring.